New Build Connection

[m4tty]

Hi,

Im working at a new build house (detached on farm) and wanted to ask a few questions.

The house is 95m from the pole which it will be fed from and the DNO wanted

 

[Andy™]

you can get TNCS from overhead, as long as the overhead line connectors etc are good enough for it. but personally, it just seems a bad idea, since its easily possible for someone to rip down the bottom line only, and there goes your earth

there is no need for a rod in meter cabinet unless its TT

extraneous bonding is nothing to do with meter monkey. if its plastic, its cant be bonded anyway. even if its metallic, it may not even be extraneous

 

[steptoe]

if he is giving you TNCS/PME from an overhead I would insist it is rodded at the bottom of the pole,

otherwise disregard their earth and TT it for yourself,

dunno what your mate is on about putting a rod in for TNS, :|

even for TNCS the rod is NOT your responsibility.

35mm 3c SWA (buried?) for a 95m run on 100A, have you calc'd your VD, (to the end of the longest circuit) ?

any DNO I have come across usually insist on main bonds being in place, incoming in plastic doesnt concern you, is the install in copper? if so it needs MEB.

 

[Revved Up Sparky]

95M of 35M SWA ?, that must have cost a bomb !

 

[Doc Hudson]

Probably less than the

 

[ProDave]

I did an install from an overhead supply a bit like this (only house was close to the pole so no need for a brick outhouse)

I was there when the DNO came. They isolated the 10KV line, removed one pole to replace it with a more substantial one to hold the transformer.

They then dug a trench both directions from the pole. The trench going away from the house they laid an HV earth (to earth the transformer), and the trench going towards the house, as well as housing the concentric supply cable to the house, they burried a length of copper for the LV earth.

So if your installation is anything similar, you should have a dependable suppliers earth, but it won't be TNCS more likely TNC

Your meter monkey was just having a bad day, as others say, his job is not to test and verify the installation, that's your job. What he should do is test the suppliers earth, and perform a polarity check after the meter is installed. That's all. Well at least that's all the DNO do up here but as we know from other discussions, what DNO's do varies a great deal over the country.

As for the cost being much higher if the supply had run direct to the house, it appears some DNO's do that. I don't think they charge much extra up here, but they do expect the customer to dig the trench on their own land, then tape and fill after the cable is laid.

 

[m4tty]

95M of 35M SWA ?, that must have cost a bomb !

About

 

[Manator]

Is it single phase or three phase? Just looking at the VD over 95 meters, would be a pain if you had to go up to 70mm

 

[Bacon]

Have just had a price for 200Mtrs 4core 50mm SWA just under

 

[m4tty]

if he is giving you TNCS/PME from an overhead I would insist it is rodded at the bottom of the pole,otherwise disregard their earth and TT it for yourself,

dunno what your mate is on about putting a rod in for TNS, :|

even for TNCS the rod is NOT your responsibility.

35mm 3c SWA (buried?) for a 95m run on 100A, have you calc'd your VD, (to the end of the longest circuit) ?

any DNO I have come across usually insist on main bonds being in place, incoming in plastic doesnt concern you, is the install in copper? if so it needs MEB.

He is doing TNCS from pole steps. I think the rod should be there too but this meter monkey would not connect unless the rod was disconnected. He tried blagging to me about mixing earthing systems but i knew he was talking rubbish. He was looking for a way to get out of doing the job as it was late in the day.

Ive done the calcs and it was actually shorter than 95M in the end and the circuits are not that long due to there being lots of circuits and the house is not massive.

Ill link to some pictures as im rubbish at explaining things.

Its a mixture of plastic and copper.

Thanks for your advice

Matt

 

[Andy™]

So if your installation is anything similar, you should have a dependable suppliers earth, but it won't be TNCS more likely TNC

dont you mean TNS, since TNC is illegal?

 

[steptoe]

2 main points Matty,

the rod is NOTHING to do with you,

DNO will/should NOT use your rod, they put their own in, or as prodave mentioned simply lay an electrode alongside the cable.

point 2,

good practice would NOT be using the black of a cable as a neutral, its not even sleeved.!

you should use the grey, or did you use the yellow in the old colours for the neutral too?

when using a 3phase cable for single phase the following is recommended :-

L1 = line

L2 = earth(sleeved)

L3 = neutral(sleeved)

oh, and either get some proper grommet strip, or better still, a 2" bush.



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[quote name='Andy

 

[Sidewinder]

m4tty,

Is that a "Henly" for the earths, is it outside, is it of a sufficient IP rating?...

 

[Manator]

I would have taken the earth into the enclosure, with a din rail mounted connecter to split if required.

 

[Sidewinder]

Quite Manator, I like my WPE16's!

 

[NozSpark]

m4tty,Is that a "Henly" for the earths, is it outside, is it of a sufficient IP rating?...

Geez Sidey,,,,

If the Henly isn't rated for outdoors then that switch fuse certainly isn't

 

[Sidewinder]

Noz,

Good point I missed that last night it looked like a plastic one, it is a metal clad by the looks of it this a.m.!

At the best IP44?

Not sure if this is inside or outside now?...

 

[gordy71]

Shouldnt a farm and any associated buildings be TT as per 705.411.4?

 

[Sidewinder]

gordy71,

705.411.4, does not require TT, it merely confirms the requirements elsewhere in 7671 & ESQCR that you must not use TN-C in a consumers installation.

The original reg group 411.4 refers to shock protection in TN systems in general.